n A bottle, flask or similar vessel having a vacuum between its inner and outer silvered walls; designed to maintain the temperature of its contents
n (context|chemistry) A Dewar vessel is the scientific version, and is most often used to store liquified gases.
n (context|chemistry) A type of glass flask used in a laboratory similar to an Erlenmeyer flask, but with a side spout used for connection to an aspirator. Also known as a Büchner flask.